Chapter 6: Microbial Growth

Question 0

facultative

Answer 0

capable of existing to more than one set of environmental conditions or by assuming various behaviors

Question 1

obligate

Answer 1

capable if surviving or functioning only in a particular condition or by assuming a particular behavior (has to have a certain thing to live)

Question 2

psychrophiles

Answer 2

cold loving microbes

Question 3

mesophiles

Answer 3

moderate temperature loving microbes. 24-40• C, most common microbe, pathogens (37•C is body temp)

Question 4

thermophiles

Answer 4

heat loving microbes(50-60•C, hot springs, soil)

Question 5

acidophiles

Answer 5

acidic loving microbes

Question 6

what pH levels do most bacteria prefer?

Answer 6

6.5-7.5

Question 7

halophiles

Answer 7

salt loving microbes; obligate halophiles require high salt concentrations in order to grow.

Question 8

aerobes

Answer 8

use oxygen in energy reactions

Question 9

anaerobes

Answer 9

do not use oxygen

Question 10

facultative anaerobes

Answer 10

use oxygen but can grow without, fermentation or anaerobic respiration

Question 11

obligate anaerobes

Answer 11

can’t use oxygen for energy reactions

Question 12

aerotolerant anaerobes

Answer 12

can’t use oxygen for growth, but can tolerate it

Question 13

microaerophiles

Answer 13

require oxygen in small amounts

Question 14

biofilm

Answer 14

communities of microbes that are attached to surfaces and share nutrients in order to grow. matrix of polysaccharides, DNA and proteins called slime.

Question 15

culture media

Answer 15

nutrient material used to grow microbes in the lab (culture)

Question 16

agar

Answer 16

solidifies the medium, polysaccharide from algae

Question 17

complex media

Answer 17

extracts from yeasts, meat and plants

Question 18

reducing media

Answer 18

for anaerobes, have ingredients that combine with and deplete oxygen

Question 19

selective media

Answer 19

suppress growth of unwanted and encourage growth of desired microbes

Question 20

differential media

Answer 20

distinguish colonies of desired organisms from others on the plate

Question 21

enrichment media

Answer 21

media specific for a microbe, used to increase numbers of an organism

Question 22

colony

Answer 22

group of the same microbe attached together

Question 23

deep-freezing

Answer 23

culture is flash frozen and can be stored for years

Question 24

lyophilization

Answer 24

flash frozen and water removed via vacuum

Question 25

binary fission

Answer 25

bacterial reproduction

Question 26

budding

Answer 26

some bacteria, yeasts; form bud out of parent cell that eventually separates

Question 27

generation time

Answer 27

time required for a cell to divide

Question 28

four phases of cell growth

Answer 28

1. lag phase
2. log phase
3. stationary
4. death

Question 29

lag phase

Answer 29

• beginning of growth, adjust to new environment
• little or no division
• 1 hour- days
• cells preparing for reproduction

Question 30

log phase

Answer 30

• cells divide, logarithmic increase

- active cells

Question 31

stationary phase

Answer 31

• growth rate slows
• # of deaths= # of new cells
• reaches equilibrium
• depletion of nutrients, build up of waste, ph change, etc

Question 32

death

Answer 32

of deaths exceeds # of new cells, logarithmic decrease, population decreases to small number or entirely

Question 33

plate counts

Answer 33

streak plate and count colonies; sometimes requires a serial dilution: dilute original culture in order to have countable number of colonies or filtration: concentrate culture so bacteria are smaller in volume

Question 34

turbidity

Answer 34

indirect way of measuring bacteria growth; use a spectrophotometer- more cloudy the sample, more bacteria.

Question 35

three indirect methods of measuring cell growth

Answer 35

turbidity, metabolic activity, dry weight

Question 36

the optimum pH for most bacteria is…?

Answer 36

7

Question 37

which organism is killed by atmospheric oxygen?

Answer 37

obligate anaerobes

Question 38

which of the following is not a possible reason why exponential growth stops?

Answer 38

a. accumulation of waste products
b. exhaustion of nutrients
c. harmful changes to pH

Question 39

a spectrophotometer can be used to measure…?

Answer 39

turbidity

Question 40

chemicals that can affect microbial growth are…

Answer 40

Carbon, nitrogen, sulfur, phosphorus, potassium, magnesium, and calcium

Question 41

organic growth factors

Answer 41

essential compounds an organism can’t synthesize (can’t make them)

Question 42

when can oxygen be toxic to microbial growth?

Answer 42

singlet oxygen- boosted into a high energy state, highly reactive(oxygens travel in twos)
superoxide radicals-produced from respiration(highly reactive)

Question 43

toxic forms of oxygen can be used on…

Answer 43

immune cells

Question 44

how to members of biofilm communities communicate?

Answer 44

quorum sensing-helps bacteria coordinate gene expression

Question 45

bacterial growth curve

Answer 45

showing growth (number of cells) over time

Question 46

most probable number method

Answer 46

method of counting bacterial colonies just using estimation

Question 47

direct microscopic count

Answer 47

colony count method just directly counting the colonies under the microscope

Question 48

coulter counters

Answer 48

electronic counters, used in research and hospitals